Automatic premeshing mechanism



Jan. 20, 1953 c. s. METSGER 7 AUTOMATIC PREMESHING MECHANISM Filed May 15, 1951 IN VEN TOR.

CHARLES S. METSGER Patented Jan. 20, 1953 AUTOMATIC PREMESHING TMECHANISM iCharles S. ;Metsger, :Rochelle Park, TN. .;I., assignor .to Bendix Aviation Corporation, Teterboro, @N. J a :corporation of Delaware Application May:15, 1951,"Seriajl' No.i226,'427

.5 Claims. '1 'The present invention relates to enginestarters and particularly to jaw meshing mechanism for use with engine starters.

With the advent of aircraft turbine engines and of larger internal combustion-engines, thepower i requirements for starters have been greatly increased. In high powered engine starters, such as the turbine type, the power element of neces- =s'ity has a high moment of inertia. Therefore, :if meshing is delayed for as little as one revolution of *the power element, severe shock is transmitted to the jaws and gearing. One means of reducing the shock is the use of torque limiting -clutches, however theyhave many limitations and many failures-due to shock-have been experienced; The present invention overcomes the above dis- .advantages .by keeping the jaws in mesh at all tim'esexcept during operation of the engine by providing a. centrifugal controlled meshing mechanism on the-engine shaft.

An object of the invention is to provide novel jaw .meshing means 'foran engine starter.

:Another .object .of ."the invention is to provide improved engine starter means.

,Another :object .of the invention is to provide means for premeshing starter and engine jaws.

Another object -of the invention is to provide novel means on the engine shaft for meshing with the starter jaw.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein two embodiments of the invention are illustrated by way of example.

In the drawings:

Figure 1 is a cross-sectional view of a portion of a starter and an engine jaw embodying the invention.

Figure 2 is an exploded view of the jaw meshing mechanism of Figure 1.

Figure 3 illustrates a modification of the invention.

Referring now to Figures 1 and 2 of the drawing, a starter 5 is provided with a housing 6. Only a fragmentary portion of the starter 5 is illustrated, it is understood however, it will comprise driving means and reduction gearing as is well known in the art. A mountin flange l is adapted to be secured to an engine housing 8 by means of studs 9 or in any other conventional manner.

An output shaft ID has splines H adapted to mate with splines I2 on starter jaw [3. The output shaft I0 is connected to the reduction gearing (not shown) by splines or in any other conventionalmanner. The shaft 18 has a coun- --terbore.portion l4 adapted to receivea spring .15. The spring 15 biases :the jaw 13 outward. The

jaw 13 is held in operative engagement with the shaft H) by retainingibolt I 6.

An engine jaw member ll, having .teeth .Iia adapted to mesh with teeth 13 .of starter jaw .43, hasasplined portion lamating with splines .20 on anextension 2| of engine shaft 22. The extension 2| may besecured to the .shaft 22 by a 10011123 or may be integral therewith. .A spring 24 is interposed between the splinedqportion 1.9 and a spring retaining member 25.. The retaining :member .25 is secured to the extension .2 l by the .bolt23.

I'he jaw zll'hasa .rampportion 26 cnthe end opposite the teeth Ha. A member 27! having .a .matingramp portion :28 .is also splined to the extension2l. A snap .ringzil holds the member 21in position. :Wedge members 3E8-arep0sitioned in the opening .formed by theramp portions 26 and 28. :wedgeymembers 32,.have agroove -3.I .thereinztoreceive agarter spring ,32. A flange :33 on the member 22 :limits the outward travel ;of thewedgesmembers. 3.8.

The jaw :13 pilots in :the housing 1 by :means of a bearing 34. An oil seal 35 surrounds the jaw l3 and is positioned in the housing I by a snap ring 36.

In operation, the garter spring 32 biases the wedge members inward with a wedging action on the ramp surfaces 26 and 23. Inasmuch as the member 21 is fixed, axial force is imparted to the jaw ll to move it against the bias of the spring 24 into engagement with the starter jaw l3. Should the teeth of the jaws abut, the spring l5 permits the jaw I3 to be retracted. Upon initial rotary movement of the jaw E3 the teeth will mesh due to the force of the spring I5.

Upon the engine shaft exceeding a predetermined speed, the wedges 30 are moved outward against the bias of the garter spring 32. The return spring 24 moves the jaw l6 out of engagement with the starter jaw l3.

As long as the engine shaft exceeds the predetermined speed, the centrifugal force overcomes the bias of the garter spring 32 and the spring 24 biases the jaw IS in the disengaged position. At a shut-down, the speed decreases, the centrifugal force decreases and the garter spring 32 forces the wedges 30 inward to move the jaw l6 towards the engaged position. The spring l5 permits the jaws to ratchet until the engine comes to a stop. The jaws remain meshed and are ready for the next start. Should the cranking speed exceed the predetermined speed, the friction between the teeth will hold the jaws in mesh until the starter ceases putting out torque.

Figure 3 illustrates a modification of the centrifugal means and comprises a ball retainer 40 of spring stock material relieved in a plurality of places 4| for true circle expansion. Balls 42 are secured in openings 43 in the retainer 40 and are adapted to be moved outward by centrifugal force. The retainer 40 has a split 44 to permit changes in diameter. The retainer 40 and balls 42 may replace the wedges 3B and garter spring 32 of Figure l. The operation is similar to that set forth for Figure 1.

Although only two embodiments of the invention have been illustrated and described, various changes in the form and relative arrangements of the parts may be made to suit requirements.

What is claimed is:

1. A starting device comprising, in combination, an engine jaw member slidably splined to an engine shaft, a fixed member on said engine shaft, means including a resilient member for biasing said engine jaw away from said fixed member, said last means also including a mass responsive to centrifugal force to overcome said bias upon said centrifugal force exceeding a predetermined value, and spring means for urging said engine jaw towards said fixed member.

2. A startin device comprising, in combination, an engine jaw member movable from a position engaging a starter jaw to a disengaged position, first spring means for biasing said engine jaw in a disengaged position, and means including second spring means for overcoming the bias of said first spring means to urge said engine jaw member into an engaging position and centrifugal means for overcoming the bias of said second spring means upon, said engine jaw exceeding a predetermined speed.

3. A starting device comprising, in combination, an engine shaft, an engine jaw member splined for axial movement relative to and rotation with said engine shaft, said engine jaw member being movable from a position engaging a starter jaw to a disengaged position, means for normally biasing said engine jaw member to a disengaged position, a ramp portion on said engine jaw member, a fixed member having an opposite ramp portion, and wedging means interposed between said ramp portions for overcoming said biasing means to urge said engine jaw member into an engaged position, said wedging means bein responsive to centrifugal force to remove the wedging action upon the speed of said engine jaw member exceeding a predetermined amount.

4. In a starting device, the combination comprising an engine shaft, an engine jaw member splined for axial movement relative to and rotation with said engine shaft, spring means for normally biasing said engine jaw member to a disengaged position, and a wedging member having a normal diameter and adapted to expand upon the action of centrifugal force, said wedging member having biasing means sufficient to overcome the bias of said spring means to urge said engine jaw to an extended position when in said normal condition and adapted to expand to remove said biasing means upon said engine jaw member exceeding a predetermined speed.

5. In a starting device, the combination comprising an engine shaft, an engine jaw member splined for axial movement relative to and rotation with said engine shaft, said jaw member being adapted for axial movement from a retracted position to an extended position, spring means for normally biasing, said jaw member to the retracted position, said jaw member having a ramp portion, and a resilient member having a normal diameter and adapted to expand upon the action of centrifugal force, said resilient member coacting with said ramp portion to overcome said spring biasing means to urge said jaw member to an extended position when in said normal condition and to permit said spring biasing means to return said jaw to a retracted 1position upon expansion of said resilient mem- CHARLES S. METSGER.

No references cited. 

